Phenetic Variation and Habitat Differences in Gasterosteus Populations of the Queen Charlotte Islands

A temporary array of land and ocean bottom seismograph stations was used to accurately locate microearthquakes on the Queen Charlotte fault zone, which occurs along the continental margin of western Canada. The continental slope has two steep linear sections separated by a 25 km wide irregular terrace at a depth of 2 km. Eleven events were located with magnitudes from 0.5 to 2.0, 10 of them beneath the landward one of the two steep slopes, some 5 km off the coast of the southern Queen Charlotte Islands. No events were located beneath the seaward and deeper steep slope. The depths of seven of these events were constrained by the data to between 9 and 21 km with most near 20 km. The earthquake and other geophysical data are consistent with a near vertical fault zone having mainly strike-slip motion. A model including a small component of underthrusting in addition to strike-slip faulting is suggested to account for the some 15° difference between the relative motion of the North America and Pacific plates from plate tectonic models and the strike of the margin. One event was located about 50 km inland of the main active zone and probably occurred on the Sandspit fault. The rate of seismicity on the Queen Charlotte fault zone during the period of the survey was similar to that predicted by the recurrence relation for the region from the long-term earthquake record.

Download Full-text

Biology of four species of Whiting (Pisces: Sillaginidae) in Botany Bay, NSW

Marine and Freshwater Research ◽

10.1071/mf9880709 ◽

1988 ◽

Vol 39 (6) ◽

pp. 709 ◽

Cited By ~ 31

Author(s):

JJ Burchmore ◽

DA Pollard ◽

MJ Middleton ◽

JD Bell ◽

BC Pease

Keyword(s):

New South ◽

Abundant Species ◽

Male And Female ◽

Fish Size ◽

South Wales ◽

Gonadal Maturity ◽

Habitat Differences ◽

Temporal And Spatial ◽

First Maturity ◽

Spatial Habitat

Four species of whiting (Family Sillaginidae) were collected from Botany Bay, New South Wales, between 1977 and 1979: Sillago ciliata (sand whiting), S. maculata maculata (trumpeter whiting), S. robusta (stout whiting) and S. bassensis flindersi (eastern school whiting). Sillago ciliata was the most abundant species over-all. Sillago ciliata was caught in greatest numbers in Zostera seagrass and shallow sandy habitats, whereas S. m. maculata, S. robusta and S. b. flindersi were most abundant over deeper muddy and sandy habitats. Sillago ciliata and S. b. flindersi were present mainly as juveniles. Gonosomatic indices and gonadal maturity stages of S. ciliata and S. m. maculata peaked around February. These species probably spawn within the Bay. Length to caudal fork at first maturity was 24 cm for male and female S. ciliata, 19 cm for male and female S. m. maculata, 17 cm for male and 18 cm for female S. robusta, and 14 cm for male and female S. b. flindersi. Although all species fed mainly on polychaetes and crustaceans, there was little overlap in specific dietary items between species. Variations observed in diet were due to fish size and temporal and spatial habitat differences within and among species.

Download Full-text

Postharvest recovery of beds of the edible red alga Porphyra perforata

Canadian Journal of Botany ◽

10.1139/b84-268 ◽

1984 ◽

Vol 62 (9) ◽

pp. 1968-1970 ◽

Cited By ~ 3

Author(s):

William G. Roland ◽

L. Michael Coon

Keyword(s):

Standing Crop ◽

Negative Impact ◽

Control Area ◽

Percent Cover ◽

Annual Fluctuation ◽

Queen Charlotte Islands ◽

Negative Effect ◽

Large Plot ◽

Small Plot ◽

Whole Plants

Recovery of intertidal Porphyra beds following hand harvest was studied near the northwest tip of the Queen Charlotte Islands, B.C. Twenty-six percent of the standing crop of Porphyra perforata J. Ag. was removed in a large plot in June 1981; no negative effect on standing crop was apparent in May 1982 as compared with the adjacent control area. There was no negative impact on percent cover of Porphyra (mostly P. perforata) within 1 year after hand harvest of seven, approximately 1-m2 plots, as compared with respective controls. Annual fluctuation in cover, biomass, and relative mix of Porphyra species was large. Porphyra cover in a small plot harvested in early June 1981 increased to 86% of the June value by mid-July 1981, indicating substantial growth of the remaining thallus fragments and small, whole plants within one season. It was concluded that sustained yield of Porphyra beds can be assured if harvest is restricted to gathering by hand.

Download Full-text